We have recently discovered that Kindler syndrome is associated with early onset periodontal disease (Wiebe et al, 2003). The mutation in practically all Kindler patients was recently localized in a novel intracellular protein named kindlin-1. Kindlin-1 is believed to be involved in the organization of actin cytoskeleton. The main goal of this research application is to unravel the functions of kindlin-1 in periodontal tissues and molecular mechanisms of initiation of periodontal disease associated with mutations in kindlin-1. Our general hypothesis is that kindlin-1 is localized in the basal cell membrane of basal keratinocytes and mediates the adhesion of basal epithelial cells to both external and internal basal laminae of the junctional epithelium. Absence of kindlin-1 weakens the link between the tooth and junctional epithelial cells, making the deficient animals susceptible to periodontal disease. The Specific Aims are: Aim 1:To investigate the localization of kindlin-1 and other proteins of the focal adhesion complex in normal, diseased and healing gingival tissue. A monoclonal antibody has been produced against kindlin-1 which will be used to localize this protein in tissues of control individuals, wounds and patients with Kindler syndrome. Aim 2:To find out the specific cellular function of kindlin-1 in keratinocyte cell adhesion and migration both in vitro and in vivo. Cell adhesion and migration on extracellular matrix proteins will be studied using normal and kindlin-1 deficient keratinocytes. Interaction of kindlin-1 with migfilin will be studied. The signaling role for kindlin-1 in regulation of basement membrane formation and type VII collagen expression will be investigated using an inclusion cyst model and organotypic cultures. Aim 3:To investigate whether mice deficient in kindlin-1 are susceptible to periodontal disease. For the study, kindlin-1 deficient transgenic mouse lines will be created and their phenotype characterized. Using a newly-established mouse model system for periodontal disease, periodontitis will be compared in control and kindlin-1 deficient mice and the extent of bone loss will be assessed.